1. Field of Invention
The present invention relates to an electrical junction box for a vehicle, in particular a box to be connected to a wire harness for a vehicle. The invention also provides a vehicle such as an automobile having the electrical junction box mounted on it.
2. Description of Related Art
Recently, the rapid increase in the number of electric and electronic component parts that are mounted on a vehicle has led to increase in the number of circuits to be accommodated in a junction box in the vehicle. When forming branch circuits at high density, it is necessary to mount a large number of component parts on the junction box, which increases the number of assembly stages.
The assignees of the present applicants proposed a junction box 1 shown in FIG. 10 in U.S. patent application Ser. No. 09/833,595. The junction box 1 of FIG. 10 is intended to be thin, capable of permitting circuit alteration and reducing time and labor when it is assembled from component parts.
In the junction box 1 of FIG. 10, a connector connection circuit (base circuit), a fuse connection circuit, and a relay connection circuit provided in the junction box 1 are formed separately as a connector module 2, a fuse module 3 and a relay module 4, respectively. The connector module 2, the fuse module 3 and the relay module 4 are incorporated in the casing composed of a lower case part 5 and an upper case part 6.
In each of the connector module 2, the fuse module 3 and the relay module 4, bus bars 2a, 3a and 4a are fixed to insulation substrates 2b, 2b and 4b, respectively, and project from the periphery of the insulation substrates where they are welded to each other.
Because the whole circuit of the junction box 1 is divided into the connector module 2, the fuse module 3 and the relay module 4, it can be avoided that tabs of the bus bars overlap on each other. Thus excessive layering of the bus bars can be prevented, and the junction box 1 can be thin. Further, the circuits of the bus bars can be wired easily. Thus it is possible to reduce the area of the bus bars of each module. Consequently, even though the connector connection bus bars 2a, the fuse connection bus bars 3a and the relay connection bus bars 4a are separately formed, it is possible to reduce the total area of the bus bars and avoid increase of the area of the junction box.
Further, when the specification of any one of the connector circuit 2, the fuse circuit 3 and the relay circuit 4 is altered, it is only necessary to alter the respective module. Thus, the junction box 1 permits alteration of the specification easily. This advantage is achieved because the entire circuit of the junction box having the connector connection circuit, the fuse connection circuit, and the relay connection circuit is divided into the connector module, the fuse module, and the relay module, respectively.
However, it is necessary to arrange the fuses of the fuse module so that they are accessible for easy replacement. Because, in this junction box 1, the fuse module 3 is placed on the connector module 2, the connector module 2 is required to be large and there are restrictions on the way in which the junction box 1 is mounted on a vehicle.
As shown in FIG. 9A, if the junction box 1 is disposed vertically behind an instrument panel 7 of a vehicle, a fuse 8 is replaced horizontally by providing the instrument panel 7 with a fuse-replacement cover 9 which is removable from the instrument panel 7. Because of the mounting of the cover 9 on the instrument panel 7, there are restrictions on the design of the instrument panel 7, and further, the instrument panel 7 may have reduced collision strength.
Accordingly, it is an object of the present invention to provide an electrical junction box suitable for a vehicle which is compact and allows fuses to be replaced easily when the junction box is disposed behind an instrument panel.
According to the present invention, there is provided an electrical junction box having a casing having an opening, a connector module providing a connector connection circuit which in use makes electrical connection to at least one electrical connector, a fuse module providing a fuse connection circuit which in use makes electrical connection to a plurality of fuses, and a relay module providing a relay connection circuit which in use makes electrical connection to at least one relay. The connector module is mounted in the casing and comprises a plurality of circuit plates stacked one on another to form a layered assembly having a pair of main faces and a plurality of sides. The fuse module includes at least one circuit plate and a plurality of fuse-receiving locations and is mounted at the opening of the casing so that the fuse-receiving locations are accessible for insertion and removal of fuses, and so that the circuit plate thereof is perpendicular to the main faces of the layered assembly of the connector module.
The width of the fuse-receiving region of the fuse module is preferably larger than the height of this region, when there are many fuses. Thus, it is possible to remove the mounting region of the fuse module from the surface of the connector module by disposing the fuse module perpendicularly to the faces of the connector module. Therefore, it is possible to reduce the length of the faces of the connector module. Accordingly, it is possible to make the junction box compact in its longitudinal direction.
The invention also provides a vehicle having the electrical connection box mounted in it. The circuit plates of the connector module are disposed vertically, and at least one location for a connector is formed on a vertical side face of the casing. The fuse module is then disposed horizontally at a lower end of the casing, and in use a plurality of fuses on the fuse module are arranged horizontally side by side adjacent a lower end surface of the casing. Thereby, with the junction box is vertically disposed, it is possible to insert fuses into the fuse module and remove them therefrom from below, even though both sides of the junction box are closed. Thus the fuse insertion and fuse removal operation is convenient.
Preferably, the circuit plate of the fuse module extends alongside and parallel to a first edge of the layered assembly of the connector module, the fuse-receiving locations of the first module are arranged in at least one straight row extending parallel to the first edge of the layered assembly and parallel to the circuit plate of the fuse module, and the direction of insertion and removal of fuses at the fuse-receiving locations is perpendicular to the circuit plate of the fuse module and perpendicular to the first edge of the layered assembly.
Preferably, the circuit plate of the fuse module includes metal bus bars which are bent out perpendicularly from its surface to provide terminals at the fuse-receiving locations to be engaged by the fuses in use.
Preferably, the relay module includes a circuit plate which is mounted in the casing parallel to the main faces of the layered assembly of the connector module and adjacent to the fuse module. The relay module is thus disposed in the casing vertical side surface proximate to the fuse module. Because the relay module is disposed proximate to the fuse module, the connection between the relay module and the fuse module is confined to a small region. Thus, it is possible to improve the work of connection.
Preferably, an electronic control unit is accommodated in the casing in such a way that it is disposed between the connector module and one side face of the casing.
Preferably, in a vehicle, the electrical junction box has a mounting bracket projecting upwardly from its casing, and the vehicle has, adjacent the electrical junction box, a body member such as a panel, an instrument panel, and a floor, the mounting bracket being fixed to the body member and the fuse-receiving locations of the fuse module facing towards the floor whereby in use the fuses are inserted and removed in a space between a lower end of the instrument panel and the floor.
With this construction, the operation of replacing the fuses on the fuse module can be accomplished perpendicularly to the floor of the vehicle, with the junction box mounted on the body panel behind the instrument panel. Thus, it is unnecessary to provide the instrument panel with an openable cover for fuse replacement for horizontal insertion and removal of the fuses. Therefore, it is possible to reduce restrictions on the design of the instrument panel and avoid reducing the strength of the instrument panel because the instrument panel does not need to be provided with the openable cover.